Pressure releaving means

ABSTRACT

A packer and method and apparatus for releasing pressure within a pressurized annulus around the packer. The apparatus comprises a central tubular member having a central bore therethrough extending between first and second ends, an outer plug slidably locatable within a first end of the tubular member and having a central bore therethrough and an inner plug slidably locatable within the central bore of the outer plug. The method comprises longitudinally retracting the inner plug from sealed engagement within the central bore of the outer plug member so as to permit fluid to flow therethrough and engaging the outer plug with a retraction body operably connected to the inner plug extending adapted to engage the inner plug after a predetermined length of travel so as to draw the outer plug out of the central tubular member thereafter.

BACKGROUND

1. Field

The present disclosure relates to methods and apparatus for isolating zones in a subterranean formation in general and in particular to methods and apparatus for releasing the pressure around sealing elements.

2. Description of Related Art

In hydrocarbon production, it is frequently desired to seal or isolate one or more zones of an oil well from adjacent zones. In such situations, a sealing element is frequently used to seal and isolate the production string to the main bore or to seal adjacent zones from each other. Such sealing elements may be components of a production packer, an open hole production packer, seal adapter, pressure chamber seal adapter (with charged high pressure chamber on board), a liner hanger packer, a full bore liner top packer, a straddle type stimulation tool, a hybrid type stimulation tools (hydroelement and mechanical packer), a hydroelement made from swellable rubber compounds, an open hole seal or a cased hole seal all of which may be mechanically, hydraulically, hydrostatically or pressure chamber operated.

Production packers are designed to be located between the casing or liner and a working or production tubing in a well. In such conventional production packers, one difficulty that exists is that the packer may be difficult to remove or retrieve after they are set. One of the reasons for this is that such packers are designed to isolate one zone from another and will therefore in practice include a pressure differential across the packer. Such pressure differential is known to impair the ability of the packer to be removed.

SUMMARY

According to embodiments there is disclosed an apparatus for releasing pressure within a pressurized annulus around a tool string of a well bore comprising a central tubular member having a central bore therethrough extending between first and second ends. The apparatus further comprises an outer plug slidably locatable within a first end of the tubular member and having a central bore therethrough and an inner plug slidably locatable within the central bore of the outer plug.

The first end cap may be operably connected to the second plug such that axial movement of the end cap retracts the second plug from the central bore of the fist plug.

The apparatus may further comprise a retraction member operably connected to and movable with the inner plug, the retracting member being adapted to engage the inner plug after a predetermined length of travel so as to draw the outer plug out of the central tubular member thereafter. The retraction member may comprise a retraction sleeve surrounding the inner plug along a parallel axis therewith. The retraction sleeve may include fluid flow passages therethrough.

The retraction sleeve may surround the outer plug and includes an inwardly oriented lip positioned to engage a corresponding outwardly oriented lip on the outer plug. The outer plug may include a centralizer body extending therefrom adapted to maintain the outer plug in axial alignment with the central bore of the tubular member after the removal of the outer plug therefrom.

According to embodiments there is disclosed a packer comprising a central tubular member having a central bore therethrough extending between first and second ends and a sealing element extending around the central tubular member adapted to be longitudinally compressed so as to axially expand the sealing element into contact with a surface of a well bore. The packer further comprises an outer plug slidably locatable within a first end of the tubular member and having a central bore therethrough and an inner plug slidably locatable within the central bore of the outer plug.

The packer may further comprise a first end cap operably connected to the second plug such that axial movement of the end cap retracts the second plug from the central bore of the fist plug. The packer may further comprise a retraction member operably connected to and movable with the inner plug, the retracting member being adapted to engage the inner plug after a predetermined length of travel so as to draw the outer plug out of the central tubular member thereafter.

The retraction member may comprise a retraction sleeve surrounding the inner plug along a parallel axis therewith. The retraction sleeve may include fluid flow passages therethrough. The retraction sleeve may surround the outer plug and includes an inwardly oriented lip positioned to engage a corresponding outwardly oriented lip on the outer plug. The outer plug may include a centralizer body extending therefrom adapted to maintain the outer plug in axial alignment with the central bore of the tubular member after the removal of the outer plug therefrom.

The sealing elements may comprise a plurality of tubular elements disposed annularly around the central member. The tubular elements may include annular springs encased therein.

The packer may further include top and bottom extrusion blocks disposed annularly around the tubular member to opposed sides of the sealing element. The top extrusion block may include an extended portion lip to engage a corresponding lip extending radially outwardly from a body secured to the inner plug after a predetermined length of travel so as to draw the top extrusion block upwards thereby releasing the sealing element.

According to embodiments there are disclosed methods for releasing pressure within a pressurized annulus of a well bore comprising providing an outer plug slidably locatable within a first end of the tubular member and having a central bore therethrough and providing a inner plug slidably locatable within the central bore of the first plug. The methods further comprise longitudinally retracting the inner plug from sealed engagement within the central bore of the outer plug member so as to permit fluid to flow therethrough and engaging the outer plug with a retraction body operably connected to the inner plug extending adapted to engage the inner plug after a predetermined length of travel so as to draw the outer plug out of the central tubular member thereafter.

The method may further comprise engaging a top extrusion block of surrounding the tubular member with the retraction body after a predetermined length of travel so as to draw the top extrusion block back thereafter.

Other aspects and features will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate embodiments wherein similar characters of reference denote corresponding parts in each view,

FIG. 1 is a cross-sectional view of a wellbore having a liner hanger according to a first embodiment located therealong.

FIG. 2 is a perspective view of the packer according to a first embodiment.

FIG. 3 is a cross sectional view of the packer of FIG. 2.

FIG. 4 is a detailed cross view of the extending arms of the packer of FIG. 2 at a first position.

FIG. 5 is a detailed exploded view of arms of the packer of FIG. 2 at a second position.

FIG. 6 is a detailed plan view of the indexing slots of FIG. 2.

FIG. 7 is a detailed layout of the indexing slots of FIG. 2.

FIG. 8 is a detailed cross view of the extending arms of the packer of FIG. 2 at a second position.

FIG. 9 is a detailed perspective view of first end of the packer of FIG. 2 at a first position.

FIG. 10 is a detailed perspective view of first end of the packer of FIG. 2 at a second position.

FIG. 11 is a detailed perspective view of first end of the packer of FIG. 2 at a third position.

FIG. 12 is a side view of the packer of FIG. 2 located within a well at an expanded position.

FIG. 13 is a detailed cross sectional view of the first and second unloader stage according to a further embodiment of the present disclosure.

FIG. 14 is a detailed perspective view of the collet arms according to a further embodiment of the present disclosure.

FIG. 15 is a detailed perspective view of the sealing elements of the packer of FIG. 2 according to a further embodiment of the present disclosure.

DETAILED DESCRIPTION

Referring to FIG. 1, a wellbore 10 is drilled into the ground 8 to a production zone 6 by known methods. The production zone 6 may contain a horizontally extending hydrocarbon bearing rock formation or may span a plurality of hydrocarbon bearing rock formations such that the wellbore 10 has a path designed to cross or intersect each formation. As illustrated in FIG. 1, the wellbore includes a vertical section 12 having a valve assembly or Christmas tree 14 at a top end thereof and a bottom or production section 16 which may be horizontal or angularly oriented relative to the horizontal located within the production zone 6. After the wellbore 10 is drilled a production string 18 is located therein with at a packer 20 to isolate a zone 19 within the well.

With reference to FIGS. 2 and 3, a packer according to a first embodiment is illustrated generally at 20. The packer 20 extends between first and second ends, 22 and 24, respectively, and is formed around a central tubular member or mandrel 26. The central mandrel 26 includes the second end 24 which is operable to have a production string 18 connected thereto according to known methods such as threading and the like. As illustrated the packer 20 includes gripping arm slips 40 proximate to the second end 24, a release section 100 proximate to the first end 22 and at least one seal element 90 between top and bottom extrusion blocks, 92 and 94.

Turning now to FIG. 3, a cross sectional view of the packer 20 is illustrated. The packer 20 includes an elongate central mandrel 26 extending between first and second ends, 28 and 30, respectively. The second end 30 of the mandrel forms the second end 24 of the packer. The mandrel 26 rotatably supports a collet arms 72 and the gripping arm slips 40 therearound as will be more fully described below.

Turning now to FIG. 4, a detailed cross sectional view of the slip 40 is illustrated. The slip 40 comprises a plurality of longitudinally extending arms 42 extending in a direction generally towards the first end 22 of the packer. The arms 42 have proximate 43 and distal ends 44 wherein the distal ends have outwardly oriented bore engaging surfaces 48 as are commonly known and an inner angled surface 46. The arms 42 include a notch 41 on the outside surface thereof for receiving a portion of the cage therein as will be more fully described below. As illustrated, the arms 42 extend substantially parallel to the mandrel 26. With reference to FIG. 5, the arms 42 may be located within slots 50 of a slip cage 52 so as maintain a relative position and alignment of the arms 42 around the mandrel 26. The arms 42 may be retained within the slip cage 54 by locating a portion 56 of the slip cage between the slots 50 and the top end of the slip cage. As illustrated. The arms 42 are also maintained proximate to the slip cage 54 with a slip housing 58 extending therearound. The slip housing 58 includes bores therethrough to permit the removal of debris from between the arms and the mandrel.

As illustrated in FIG. 4, each arm includes at least one bore 64 in a bottom thereof sized to receive a biasing pin 66 with a corresponding spring 68. The bores 64 are located with the inwardly oriented surface of the arms between the notch 41 and the proximate ends 43. The biasing pins 66 extend from the bores 64 to engage upon the slip housing so as to bias the arms to a retraced position.

The slip 40 includes a cone 60 associated therewith comprising a tubular body slidably located around the mandrel 26. The cone 60 includes an angled trailing surface 62 corresponding to the bottom surface 46 of the arms 42.

The slip 40 further includes a drive housing 70 located towards the second end 24 of the packer 20. The drive housing 70 comprises a tubular body engaging with and abutting against the slip housing 58 and the slip cage 52 so as to be operable to move the slip housing, slip cage and arms longitudinally along the mandrel. The drive housing further includes a plurality of longitudinally extending collet arms 72 extending in a direction towards the second end 24 of the packer. The collet arms include a radially extended contact surface 74 and are radially flared from the packer as illustrated in FIGS. 2 and 3 so as to cause the contact surface 74 to engage upon the liner of the wellbore and cause drag therewith. The contact surfaces 74 may be substantially the same width as the collet arms 72 or may optionally have tapered edges as illustrated in FIG. 14 to provide additional space for fluid flow therepast.

As illustrated in FIG. 4, the drive housing includes a plurality of pins 76 extending radially inwardly therefrom which are received with in a profiled groove 78 on the outside surface of the mandrel. With reference to FIG. 6 a perspective view of the mandrel 26 is illustrated. The profiled groove 78 extends around the mandrel 26 and includes a plurality of indexing notches 80 located along the edge towards the second end 24 of the packer. The profiled groove 78 further includes alternating long and short slots, 82 and 84, respectively along the edge towards the first end 22 of the packer. The indexing notches 80 are arranged to be located intermediate the long and short 82 and 84 slots with angled walls 86 and 88 on one side thereof each so as to cause the pins 76 to be alternatingly advanced between the long and short slots as the mandrel is cycled forwards and backwards relative to the drive housing as illustrated in FIG. 7. When the pins 76 are located within the short slots, the drive housing will be prevented from moving towards the first end 22 of the packer thereby preventing the arms 42 from being extended. When the pins 76 are located within the long slots 84, the drive housing 70 will be permitted to move towards the first end 22 thereby extending the arms 42.

With reference to FIG. 3, the packer 20 includes seal elements 90 located around the mandrel 26 at a position towards the first end 22 from the arms 42 between the top and bottom extrusion blocks 92 and 94. The bottom extrusion block is secured to the cone 60 and the top extrusion block is secured to the mandrel 26. As illustrated in FIG. 8, when the pins 76 are located within the long slots 84 and the mandrel pressed toward the second end 24, the arms 42 will extend engaging the well bore wall. Further pressure applied to the mandrel 26 toward the second end 24 will press compress the mandrel 26, seal elements 90 and top extrusion block towards the second end 24 of the packer so as to compress the seal elements 90 between the top and bottom extrusion blocks 92 and 94 thereby expanding the seal into contact with the well bore wall as illustrated in FIG. 12. As illustrated in FIG. 15, the seal elements may include at least one annular spring element 95 therein providing a radially non-compressible core in each seal element so as to prevent the seal element 90 from extruding past the top or bottom extrusion block. The seal elements 90 may also include a spacer therebetween 93. As illustrated in FIGS. 3, the packer may include 3 seal elements 90 however it will be appreciated that more or less than 3 may also be utilized.

Turning now to FIG. 9, the release section 100 located proximate to the first end 22 of the packer 20 is illustrated. The release section includes a top collar 102 forming the first end 22 of the packer. The top collar 102 may include a threaded bore 104 into the end thereof for connection to the production string as is commonly known. The release section 100 includes a bypass mandrel 106 secured to the top collar 102 with first and second bypass plugs, 108 and 110 respectively. The first and second bypass plugs 108 and 110 are adapted to sequentially permit an increasing amount of material past the packer as will be more fully described below.

As illustrated in FIGS. 9 through 11, the bypass mandrel 106 is secured to the top collar 102 at a first end 112 of thereof. The first bypass plug 108 is secured with within a bore 114 at a second end 116 of the bypass mandrel by fasteners 118 or the like. The first bypass plug 108 comprises a body having a cylindrical seal section 120 with at least one seal 122 extending therearound which is sized to be sealably received within a corresponding bore 130 of the second bypass plug 110. As illustrated in FIG. 9, the first bypass plug 108 may include two seals, however it will be appreciated that one or three or more seals 122 may also be utilized as illustrated in FIG. 13.

The second bypass plug 110 comprises a tubular body extending between first and second ends, 132 and 134 respectively and having a central bore 130 extending therethrough. The second bypass plug 110 includes a cylindrical seal section 136 extending from the second end 134 with at least one seal 138 extending therearound. As illustrated in FIG. 9, the second bypass plug 110 may include two seals, however it will be appreciated that one or three or more seals may also be utilized. The central mandrel 26 includes a central bore 140 sized to sealably receive the seal section 136 of the second bypass plug 110 therein. The second bypass plug 110 may include a centralizing extension 142 extending therefrom for maintaining the second bypass plug 110 in axial alignment with the central mandrel 26 when the second bypass plug 110 is removed therefrom as illustrated in FIG. 11. As illustrated in FIG. 13, the first bypass plug 108 may also include a radiued annular flange 115 sized and shaped to be sealably received against a corresponding filleted recession 117 in the first end 132 of the second bypass plug 110 around the central bore 130 thereof. When the first bypass plug 108 is engaged within the central bore 130 of the second bypass plug 110, it will be appreciated that the annular flange 115 will bear against the recession to provide an additional seal therebetween.

With reference to FIG. 10, when a user wishes to release the packer, the top collar 102 is drawn in a direction generally indicated at 160 away from the second end 24 of the packer. The top collar 102 pulls the bypass mandrel 106 with it drawing the first bypass plug 108 so as to disengage it from the central bore 130 of the second bypass plug 110 thereby permitting full flow of material therethrough in a direction generally indicated at 170. The bypass mandrel 106 includes an extension sleeve 144 with a distal interior ridge 146. The interior ridge 146 is adapted to engage a corresponding exterior ridge 148 on the first end 132 of the second bypass plug 110. When the travel of the top collar 102 and bypass mandrel 106 engages the interior ridge 146 upon the exterior ridge 148. As illustrated in FIG. 11, subsequent movement of the top collar 102 and bypass mandrel 106 will also draw the second bypass plug 110 so as to disengage it from the central bore 140 of the central mandrel 26 thereby permitting full flow of material therethrough in a direction generally indicated at 172.

As illustrated in FIG. 11, the central mandrel 26 includes and extension sheath 150 extending from the first end 28 thereof. The extension sheath includes an interior ridge 152 at a distal end 156 thereof adapted to engage an exterior ridge 154 on the bypass mandrel 106. When the top cap 102 and bypass mandrel 106 reaches a sufficient distance for the interior and exterior ridges 152 and 154 to engage each other, the extension sheath 150 and thereby the central mandrel 26 will be drawn in the retraction direction as well. It will be appreciated that movement of the central mandrel 26 will cause the cone 60 to be pulled away from the arms 42 thereby permitting the arms to disengage from the well bore wall as well as decompressing the sealing elements. Thereafter the entire packer 20 may be removed or repositioned as desired. If the packer 20 is desired to be repositioned, it may be positioned at the desired location in the well and a downward force applied

While specific embodiments have been described and illustrated, such embodiments should be considered illustrative only and not as limiting the disclosure as construed in accordance with the accompanying claims. 

What is claimed is:
 1. An apparatus for releasing pressure within a pressurized annulus around a tool string of a well bore comprising: a central tubular member having a central bore therethrough extending between first and second ends; an outer plug slidably locatable within a first end of the tubular member and having a central bore therethrough; and an inner plug slidably locatable within the central bore of said outer plug.
 2. The apparatus of claim 1 further comprising a first end cap operably connected to the second plug such that axial movement of the end cap retracts said second plug from said central bore of said fist plug.
 3. The apparatus of claim 2 further comprising a retraction member operably connected to and movable with said inner plug, said retracting member being adapted to engage said inner plug after a predetermined length of travel so as to draw said outer plug out of the central tubular member thereafter.
 4. The apparatus of claim 3 wherein said retraction member comprises a retraction sleeve surrounding said inner plug along a parallel axis therewith.
 5. The apparatus of claim 4 wherein said retraction sleeve includes fluid flow passages therethrough
 6. The apparatus of claim 4 wherein said retraction sleeve surrounds said outer plug and includes an inwardly oriented lip positioned to engage a corresponding outwardly oriented lip on said outer plug.
 7. The apparatus of claim 1 wherein said outer plug includes a centralizer body extending therefrom adapted to maintain said outer plug in axial alignment with said central bore of said tubular member after the removal of said outer plug therefrom.
 8. A packer comprising: a central tubular member having a central bore therethrough extending between first and second ends; a sealing element extending around said central tubular member adapted to be longitudinally compressed so as to axially expand said sealing element into contact with a surface of a well bore; an outer plug slidably locatable within a first end of the tubular member and having a central bore therethrough; and an inner plug slidably locatable within the central bore of said outer plug.
 9. The packer of claim 8 further comprising a first end cap operably connected to the second plug such that axial movement of the end cap retracts said second plug from said central bore of said fist plug.
 10. The packer of claim 9 further comprising a retraction member operably connected to and movable with said inner plug, said retracting member being adapted to engage said inner plug after a predetermined length of travel so as to draw said outer plug out of the central tubular member thereafter.
 11. The packer of claim 10 wherein said retraction member comprises a retraction sleeve surrounding said inner plug along a parallel axis therewith.
 12. The packer of claim 11 wherein said retraction sleeve includes fluid flow passages therethrough
 13. The packer of claim 11 wherein said retraction sleeve surrounds said outer plug and includes an inwardly oriented lip positioned to engage a corresponding outwardly oriented lip on said outer plug.
 14. The packer of claim 8 wherein said outer plug includes a centralizer body extending therefrom adapted to maintain said outer plug in axial alignment with said central bore of said tubular member after the removal of said outer plug therefrom.
 15. The packer of claim 8 wherein said sealing elements comprises a plurality of tubular elements disposed annularly around said central member.
 16. The packer of claim 15 wherein said tubular elements include annular springs encased therein.
 17. The packer of claim 1 further including top and bottom extrusion blocks disposed annularly around said tubular member to opposed sides of said sealing element.
 18. The packer of claim 17 wherein said top extrusion block includes an extended portion lip to engage a corresponding lip extending radially outwardly from a body secured to said inner plug after a predetermined length of travel so as to draw said top extrusion block upwards thereby releasing said sealing element.
 19. A method for releasing pressure within a pressurized annulus of a well bore, the method comprising: providing a outer plug slidably locatable within a first end of the tubular member and having a central bore therethrough; and providing a inner plug slidably locatable within the central bore of said first plug; longitudinally retracting said inner plug from sealed engagement within said central bore of said outer plug member so as to permit fluid to flow therethrough; and engaging said outer plug with a retraction body operably connected to said inner plug extending adapted to engage said inner plug after a predetermined length of travel so as to draw said outer plug out of the central tubular member thereafter.
 20. The method of claim 19 further comprising engaging a top extrusion block of surrounding said tubular member with said retraction body after a predetermined length of travel so as to draw said top extrusion block back thereafter. 